From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758620Ab0E0Uyw (ORCPT ); Thu, 27 May 2010 16:54:52 -0400 Received: from smtp-out.google.com ([74.125.121.35]:27201 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750968Ab0E0Uyv (ORCPT ); Thu, 27 May 2010 16:54:51 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:x-system-of-record; b=OYoE4hoGNsn/uGRIGJGlkngFl/AilOXz1LKLoik/n/FWJ8aTuOhuSTz5WNBMcIBrM 0cLs5kjR1gLUd+dgRRIpQ== MIME-Version: 1.0 In-Reply-To: <20100527184135.GL9874@ghostprotocols.net> References: <20100503203813.GA17886@sharma-home.net> <1272919356.1642.154.camel@laptop> <1272964598.5605.133.camel@twins> <20100505181612.GA5091@sharma-home.net> <20100527184135.GL9874@ghostprotocols.net> Date: Thu, 27 May 2010 13:54:46 -0700 Message-ID: Subject: Re: [PATCH] perf: implement recording/reporting per-cpu samples From: Arun Sharma To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, fweisbec@gmail.com Content-Type: text/plain; charset=UTF-8 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 27, 2010 at 11:41 AM, Arnaldo Carvalho de Melo wrote: > Em Wed, May 05, 2010 at 11:16:12AM -0700, Arun Sharma escreveu: >> On Tue, May 04, 2010 at 11:16:38AM +0200, Peter Zijlstra wrote: >> > > In a shared multi-core environment, users want to analyze why their >> > > program was slow. In particular, if the code ran slower only on >> > > certain CPUs due to interference from other programs or kernel >> > > threads, they want to know that. >> > >> > But for that you use perf record -a, right? So you record all cpus >> > allways -- otherwise there is no telling what was happening to make it >> > go slow. >> >> The updated patch records the CPU only in the system_wide mode. > > I think this should be done only if you'll actually need it, as in, > "cpu" is one of the sort keys, but that can be done as a followup patch, > but there is another thing I think you need to change, see below. > How would you know if the user is going to sort by cpu at "perf record" time? Thanks for taking care of the second part. -Arun